unfold junctions at compile time sometimes.
build a new "is_from_core".
fixed junction ops, fixed is_from_core, added %!foldable_junction
the optimisation works for while/until, too.
a bit prettier code.
allow any and all, use a hash for the outer check.
simplify can_chain_junction_be_warped.
bail out before doing any analysis

analysis in this case doesn't contribute anything helpful
to the process, unlike the "call to &foo with arguments (bar)
will never work" for example.
remove any/all again due to flattening woes
why not make this a level 2 optimization? :)
Merge pull request #101 from timo/junction-opt

Partially inline junctions in bool context at compile time